Effects of growth hormone and feeding level on endocrine measurements,hormone receptors,muscle growth and performance of prepubertal heifers

Prepubertal Friesian heifer calves (n = 24, initial BW = 195 +/- 5 kg) were assigned to a 2 x 2 factorial block design and used to evaluate the effects of daily GH treatment (0 or 15 mg/d) at either a low or a high feeding level in a 5-wk treatment period on endocrine measurements, hormone receptors, muscle growth, and overall performance. In the pretreatment period, a low feeding level was employed for all calves. During the treatment period, animals at the low feeding level had free access to a roughage-based mixture, whereas animals at the high feeding level had free access to a concentrate mixture and were offered 2 kg/d of the roughage-based mixture. Blood samples were collected weekly starting 3 wk before treatment. Longissimus (LM) and supraspinatus (SS) muscles were obtained at slaughter. Metabolizable energy intake was 81% higher, digestible CP intake was 140% higher, and ADG was 115% higher (all P < 0.001) at the high vs. low feeding level. Feed (DMI, ME, and protein) intake was not affected by GH treatment, but ADG was 18% higher (P < 0.13) in GH-treated than in control heifers at both feeding levels. Although of different magnitudes, the muscle anabolic effects of GH treatment and high vs. low feeding level were additive, and both treatments increased carcass weights (P < 0.02 and P < 0.001, respectively), LM (P < 0.05 and P < 0.001), and SS (P < 0.06 and P < 0.003). The anabolic effect of GH treatment was similar in both muscles, whereas the effect of feeding level was most pronounced in LM. Overall, GH treatment increased plasma GH, IGF-I (both P < 0.001), and IGFBP-3 (P < 0.02); however, GH treatment increased total IGF-I, free IGF-I, and IGFBP-3, and decreased IGFBP-2 mainly at the high feeding level (GH x feeding level interaction; P < 0.02, 0.01, 0.03, and 0.10, respectively). The high feeding level increased insulin, free and total IGF-I, and IGFBP-3 (all P < 0.001), but decreased GH and IGFBP-2 (both P < 0.001). High feeding increased type-1 IGF receptor density (P < 0.02), mainly in LM, in accordance with the largest anabolic response in this muscle, whereas GH treatment had no effect on type-1 IGF receptors. The results suggest that in skeletal muscle, the anabolic effects of exogenous GH are related to endocrine changes in the GH-IGF axis, whereas the effects of feeding level also seem to rely on IGF receptor density in the muscles.     

The occurrence of equine arteritis virus in Australia

This paper reports the first isolation of equine arteritis virus (EAV) in Australia and serological evidence of exposure to EAV in Australian horses. Twelve Standardbred stallions imported from North America were found to shed EAV in semen. One hundred and seven stallions were tested for serum antibodies to EAV and 73% of Standardbred stallions tested were seropositive as compared to 8% of Thoroughbred stallions. Serum antibody was detected in 71% of Standardbred mares, 6% of Standardbred racehorses and 1% of Thoroughbred mares and racehorses. Examination of stored serums demonstrated that EAV had been present in Australia since at least 1975.     

Organic Glasses: A New Class of Photorefractive Materials

The performance of amorphous organic photorefractive (PR) materials in applications such as optical data storage is generally limited by the concentration of active molecules (chromophores) that can be incorporated into the host without forming a crystalline material with poor optical quality. In polymeric PR systems described previously, performance has been limited by the necessity of devoting a large fraction of the material to inert polymer and plasticizing components in order to ensure compositional stability. A new class of organic PR materials composed of multifunctional glass-forming organic chromophores is described that have long-term stability and greatly improved PR properties.     

Predatory Dinosaurs from the Sahara and Late Cretaceous Faunal Differentiation

Late Cretaceous (Cenomanian) fossils discovered in the Kem Kem region of Morocco include large predatory dinosaurs that inhabited Africa as it drifted into geographic isolation. One, represented by a skull approximately 1.6 meters in length, is an advanced allosauroid referable to the African genus Carcharodontosaurus. Another, represented by a partial skeleton with slender proportions, is a new basal coelurosaur closely resembling the Egyptian genus Bahariasaurus. Comparisons with Cretaceous theropods from other continents reveal a previously unrecognized global radiation of carcharodontosaurid predators. Substantial geographic differentiation of dinosaurian faunas in response to continental drift appears to have arisen abruptly at the beginning of the Late Cretaceous.     

Somatomedins

Somatomedin is the name for the hormone or hormones that mediate the effects of growth hormone. The suggestion of this term in 1972 represented establishment of a new theory concerning growth hormone action and growth regulation. The development and present status of the theory is reviewed. A discussion of factors affecting somatomedin level in serum leads to conclusions regarding practical use of somatomedin determinations. Levels of somatomedin can only be determined by bioassay because somatomedin is not chemically identified. The need for international coordination of the work on somatomedin is emphasized.

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Kurzfassung Somatomedin ist die Bezeichnung für das Hormon bzw. die Hormone die die Wirkung des Wachstumshormons überführen. Der Vorschlag dieser Bezeichnung von 1972 repräsentierte die Aufstellung einer neuen Theorie betreffs Wachstumshormonwirkung und Wachsregulierung. Die Entwicklung sowie der augenblickliche Stand der Theorie ist besprochen worden. Die Diskussion über die Faktoren die auf dem Somatomedinniveau im Serum einwirken, führten Konklusionen betreffs der praktischen Anwendung der Somatomedinbestimmung mit sich. Das Somatomedinniveau kann nur durch biologische Methoden bestimmt werden weil die chemische Natur des Somatomedin noch nicht identifiziert ist. Der Bedarf internationaler Koordination über Arbeiten von Somatomedin ist nachdrücklich betont.Riassunto Somatomedina è la denominazione di un ormone o degli ormoni intermediari dell'ormone della crescita. Questa recente definizione (1972) costituisce una nuova teoria sull'azione degli ormoni della crescita e della regolazione stessa della crescita. L'autore fa il punto sullo sviluppo e sullo stato attuale di questa teoria. La discussione dei fattori che influiscono sul tasso delle somatomedine nel siero sanguigno, porta a indicazione sull' utilizzazione pratica del loro dosaggio che deve essere effettuato con un metodo biologico, visto che la composizione chimica di questo ormone non è nota. Si sottolinea la necessità di una coordinazione sul piano internazionale dei lavori sulle somatomedine.

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Resume La somatomédine est la dénomination d'une hormone ou des hormones médiatrices des hormones de la croissance. Cette appellation récente (1972) ne constitue en fait qu'une nouvelle théorie de l'action des hormones de la croissance et de la régulation même de la croissance. L'auteur résume l'évolution de cette théorie jusqu'à ce jour. En discutant des conditions qui influent sur le taux de somatomédine dans le sérum sanguin, il donne des indications sur l'utilisation pratique du dosage qui ne peut être effectué que par une méthode biologique, la composition chimique de cette hormone n'étant pas encore complètement connue. L'intérêt d'une coordination des travaux sur le plan international est souligné.

     

Reticulosis of the visual system in a dog

A 7-year-old male Kerry Blue Terrier had been compensating for a visual deficit for approximately 2 months. Five days before examination, the dog had suddenly lost all vision and the pupils had become widely dilated and unresponsive to light. Ophthalmic examination revealed inflammation of the optic discs. Response to therapy was favourable but temporary.
Post mortem findings consisted of granulomatous optic neuritis, meningoencephalitis and chorioretinitis, similar to reticulosis.